1. Field of the Invention
The present invention relates generally to the field of data communications, and more particularly to a method and apparatus for distributed processing for optimal quality of service (QOS) in a broadband access system.
2. Description of the Related Art
In broadband access systems such as cable modem systems, particularly wireless ones, the overall system environment is dynamic. For example, modems may come-on-line or drop-off as users log-on or log-off the system. Furthermore, extensions and taps may be added to the CATV cable system. In wireless systems, multi-path and fading cause changes in the operating environment, as do changes in temperature and even the time of year. Also, various other conditions are outside the control of the system operator. In addition, system capabilities may be added and dropped from the base station at any time.
All of these system variations require a system operator to constantly monitor and update the system parameters, in order to provide for optimal operational efficiency and data throughput. Since this is a complex and highly interactive process, system changes are generally done infrequently. In fact, most system operators currently set a minimum data rate in a channel to prevent any problems under the worse possible conditions. This results in poorer data rates than might otherwise be possible. For example, many wireless systems are capable of operating at 64 QAM with a 5 megasymbol rate, but this operating environment requires a very good signal-to-noise ratio (SNR), and virtually no multi-path. Thus, in practice, system operators set the operating conditions to 16 QAM or QPSK, or to a slower symbol rate, in order to ensure the system will function even under various anomalous conditions. This results in a less than optimal system operating condition.
System performance could be improved if the system parameters were frequently adjusted to take advantage of the changing conditions. The process of monitoring an access system could be automated, but an automatic system would require a large and complex operating algorithm to determine what changes could be made, and how best to make those changes for each modem in the system. This process becomes exponentially more difficult as more modems are added on-line. Polling the modems for the quality of their received downstream signal also increases the traffic on the network and thereby reduces the net data throughput.
Thus, it would be desirable to be able to control the quality of service in a broadband access system, without requiring the manual adjustment of the system operational parameters and without significantly increasing the system over-head.